I hear the NOAA forecast provide the estimated location of the GS as in X NM east of certain locations. Using that info it one can plot it, and then as implied by FSMIKE use your GPS
. However other than that, it seems like pure observation.
In South Florida the water color changes once you leave the 20-40' depths and enter the 500' depths 3 NMs out. Yet, I assume that is still not the GS. Am I correct?